Physics

In this paper we describe the evolution of the Universe in terms of the Friedmann equation, which takes into account of the composition and geometry of the Universe. The dependence of the solution on the geometry and composition for different combinations of the basic constituents are discussed. The distinct behaviors for the temporal evolution of the Universe are determined and the scenario predicted by the Standard Cosmology is presented.

Seasonality is one of the oldest and most elucidation-resistant issues in suicide epidemiological research. Despite winter depression (also known as Seasonal Affective Disorder, SAD) is known and treated since many years, worldwide cross-sectional data from 28 countries show a lower frequency of suicide attempts around the equinoxes and a higher frequency in spring (both in Northern and Southern Hemisphere). This peak is not compatible with the SAD explanation. However, in recent years epidemiological research has yielded new results, which provide new perspectives on the matter. In fact, the discovery of a new pathology called Post-Series Depression (PSD) could provide an explanation of the suicide attempts pattern. The aim of this study is to analyse weekly data in order to compare them with the TV series broadcasting. Since medical observations in our sample are distributed over many years, in order to compare them as best as we can with the television programming, Grey's Anatomy series was chosen. This medical drama has been in the top 10 of most viewed TV series since 12 years and it is broadcast all over the world, so that it can be considered a universal and homogeneous phenomenon. A full season of the series is split into two separate units with a hiatus around the end of the calendar year, and it runs from September through May. Data analysis was made in order to prove the correlation between PSD and the increase of suicide attempts. Surprisingly, the data analysis shows that the increase of rate of suicide attempts does not coincide with the breaks in Grey's Anatomy scheduling, but with the series broadcasting. This therefore suggests that it is the series itself to increase the viewer's depression.

A popular physics legend holds that scissors can cut paper with a speed faster than light. Here this counter-intuitive myth is investigated theoretically using four simple examples of scissors. For simplicity, all cases will involve a static lower scissors blade that remains horizontal just under the paper. In the first case, the upper blade will be considered perfectly rigid as it rotates around and through the paper, while in the second case, a rigid upper blade will drop down to cut the paper like a guillotine. In the third case, the paper is cut with a laser rotating with a constant angular speed that is pointed initially perpendicular to the paper at the closest point, while in the fourth case, the uniformly rotating laser is pointed initially parallel to the paper. Although details can be surprising and occasionally complex, all cases allow sections of the paper to be cut faster than light without violating special relativity. Therefore, the popular legend is confirmed, in theory, to be true.

In this paper we examine more deeply about the bending mechanism of rod-shaped fireworks which burned from the free end. We derived new analytic equations. Surprisingly, we obtained the bending patterns are similar to the cornu spiral. With a few simple steps we proved that positions of points throughout the fireworks are given by Fresnel integrals, C(x) and S(x), which are generally found in phenomena of electromagnetic wave diffraction. Although we deeply discussed bending of fireworks rods, however the proposed method is likely to explain any phenomena in nature related to an evolving length scale associated with some material that becomes progressively stiff or dry, such as the growth of resin exuded from trees.

The ancient Chinese bridge, Luoyang Bridge, has been revealed to obey similar laws to diminish waves, like an optical model, metagrating. Numerical simulations have been performed to verify this finding.

In the framework of the approach of Dyson megastructures, by assuming that a super-advanced civilization exists and is capable of constructing a ring-like megastructure around their host star, we have considered the observational signatures of cold (300 K) and hot (4000) K astro-engineering to answer the question: are the modern facilities capable to detect theoretically predicted fingerprints? By implying the spectral resolving power and the radial velocity methods it has been shown that the oscillation of the rings might be detected as anomalous variability of the megastructures.

The underlying physics of basketball shooting seems to be a straightforward example of the Newtonian mechanics that can easily be traced by numerical methods. However, a human basketball player does not make use of all the possible basketball trajectories. Instead, a basketball player will build up a database of successful shots and select the trajectory that has the greatest tolerance to small variations of the real world. We simulate the basketball player's shooting training as a Monte Carlo sequence to build optimal shooting strategies, such as the launch speed and angle of the basketball, and whether to take a direct shot or a bank shot, as a function of the player's court positions and height. The phase space volume that belongs to the successful launch velocities generated by Monte Carlo simulations are then used as the criterion to optimize a shooting strategy that incorporates not only mechanical, but human factors as well.

It seems reasonable that a toroid can be thought of approximately as a solenoid bent into a circle. The correspondence of the inductances of these two objects gives an approximation for the natural logarithm in terms of the average of two numbers. Different ways of averaging give different approximants. They are expressions simpler than Taylor polynomials, and are meaningful over a wider domain.

This paper outlines some of the difficulties faced by archaeologists studying human activity in outer space. The International Space Station Archaeological Project has identified solutions to these problems, including the use of historic photographic archives and documentation of discard practices such as processes associated with the return of space-flown items to Earth.

As we discover numerous habitable planets around other stars in the Milky Way galaxy, including the nearest star, Proxima Centauri, one cannot help but wonder why have we not detected evidence for an advanced alien civilization as of yet. The surfaces of other planets might show either relics of advanced civilizations that destroyed themselves by self-inflicted catastrophes or living civilizations that are technologically primitive. Such circumstances can only be revealed by visiting those planets and not by remote observations.